musl/src/thread, branch v1.1.18 musl - an implementation of the standard library for Linux-based systems fix read-after-free type error in pthread_detach 2017-10-14T03:00:34+00:00 Rich Felker dalias@aerifal.cx 2017-10-14T03:00:34+00:00 c1e27367a9b26b9baac0f37a12349fc36567c8b6 calling __unlock on t->exitlock is not valid because __unlock reads the waiters count after making the atomic store that could allow pthread_exit to continue and unmap the thread's stack and the object t points to. for now, inline the __unlock logic with an unconditional futex wake operation so that the waiters count is not needed. once __lock/__unlock have been made safe for self-synchronized destruction, we could switch back to using them. 
calling __unlock on t->exitlock is not valid because __unlock reads
the waiters count after making the atomic store that could allow
pthread_exit to continue and unmap the thread's stack and the object t
points to. for now, inline the __unlock logic with an unconditional
futex wake operation so that the waiters count is not needed.

once __lock/__unlock have been made safe for self-synchronized
destruction, we could switch back to using them.
fix signal masking race in pthread_create with priority attributes 2017-09-07T00:37:19+00:00 Rich Felker dalias@aerifal.cx 2017-09-07T00:37:19+00:00 9e01be6e49b9ae433072207f420ef33c8189eb78 if the parent thread was able to set the new thread's priority before it reached the check for 'startlock', the new thread failed to restore its signal mask and thus ran with all signals blocked. concept for patch by Sergei, who reported the issue; unnecessary changes were removed and comments added since the whole 'startlock' thing is non-idiomatic and confusing. eventually it should be replaced with use of idiomatic synchronization primitives. 
if the parent thread was able to set the new thread's priority before
it reached the check for 'startlock', the new thread failed to restore
its signal mask and thus ran with all signals blocked.

concept for patch by Sergei, who reported the issue; unnecessary
changes were removed and comments added since the whole 'startlock'
thing is non-idiomatic and confusing. eventually it should be replaced
with use of idiomatic synchronization primitives.
trap UB from attempts to join a detached thread 2017-08-12T00:42:30+00:00 Rich Felker dalias@aerifal.cx 2017-08-12T00:42:30+00:00 80bf5952551c002cf12d96deb145629765272db0 passing to pthread_join the id of a thread which is not joinable results in undefined behavior. in principle the check to trap does not necessarily work if pthread_detach was called after thread creation, since no effort is made here to synchronize access to t->detached, but the check is well-defined and harmless for callers which did not invoke UB, and likely to help catch erroneous code that would otherwise mysteriously hang. patch by William Pitcock. 
passing to pthread_join the id of a thread which is not joinable
results in undefined behavior.

in principle the check to trap does not necessarily work if
pthread_detach was called after thread creation, since no effort is
made here to synchronize access to t->detached, but the check is
well-defined and harmless for callers which did not invoke UB, and
likely to help catch erroneous code that would otherwise mysteriously
hang.

patch by William Pitcock.
unify the use of FUTEX_PRIVATE 2017-07-04T21:12:52+00:00 Jens Gustedt Jens.Gustedt@inria.fr 2017-06-24T08:18:05+00:00 d906fa3118c888227d858b6d642a09e055eca2b4 The flag 1<<7 is used in several places for different purposes that are not always easy to distinguish. Mark those usages that correspond to the flag that is used by the kernel for futexes. 
The flag 1<<7 is used in several places for different purposes that are
not always easy to distinguish. Mark those usages that correspond to the
flag that is used by the kernel for futexes.
use hard-coded sh4a atomic opcodes to avoid linker errors on sh 2017-06-08T23:44:27+00:00 Rich Felker dalias@aerifal.cx 2017-06-08T23:44:27+00:00 bc313e880c6cde2e512d2f43e84968d1b12bd19d when using the sh4a opcodes, the assembler tags the resulting object file as requiring sh4a. the linker then refuses to (static) link it with object files marked as requiring j2, since there is no isa level that includes both sh4a and j2 instructions. 
when using the sh4a opcodes, the assembler tags the resulting object
file as requiring sh4a. the linker then refuses to (static) link it
with object files marked as requiring j2, since there is no isa level
that includes both sh4a and j2 instructions.
fix build regression in arm atomics asm with new binutils 2017-02-15T22:50:47+00:00 Rich Felker dalias@aerifal.cx 2017-02-15T22:05:50+00:00 b261a24256792177a5f0531dbb25cc6267220ca5 binutils commit bada43421274615d0d5f629a61a60b7daa71bc15 tightened immediate fixup handling in gas in such a way that the final .arch of an object file must be compatible with the fixups used when the instruction was assembled; this in turn broke assembling of atomics.s, at least in thumb mode. it's not clear whether this should be considered a bug in gas, but .object_arch is preferable anyway for our purpose here of controlling the ISA level tag on the object file being produced, and it's the intended directive for use in object files with runtime code selection. research by Szabolcs Nagy confirmed that .object_arch is supported in all relevant versions of binutils and clang's integrated assembler. patch by Reiner Herrmann. 
binutils commit bada43421274615d0d5f629a61a60b7daa71bc15 tightened
immediate fixup handling in gas in such a way that the final .arch of
an object file must be compatible with the fixups used when the
instruction was assembled; this in turn broke assembling of atomics.s,
at least in thumb mode.

it's not clear whether this should be considered a bug in gas, but
.object_arch is preferable anyway for our purpose here of controlling
the ISA level tag on the object file being produced, and it's the
intended directive for use in object files with runtime code
selection. research by Szabolcs Nagy confirmed that .object_arch is
supported in all relevant versions of binutils and clang's integrated
assembler.

patch by Reiner Herrmann.
fix spurious EINTR errors from multithreaded set*id, etc. 2017-01-19T16:45:01+00:00 Rich Felker dalias@aerifal.cx 2017-01-19T16:45:01+00:00 6894f8472614e22c76820b6469d2551d17e024ed commit 78a8ef47c4d92b7680c52a85f80a81e29da86bb9 inadvertently removed the SA_RESTART flag from the sigaction for the internal signal handler used by __synccall for broadcasting. as a result, programs which did not use interrupting signals but which used set*id() in a multithreaded context could wrongly observe EINTR errors they're not prepared to handle. 
commit 78a8ef47c4d92b7680c52a85f80a81e29da86bb9 inadvertently removed
the SA_RESTART flag from the sigaction for the internal signal handler
used by __synccall for broadcasting. as a result, programs which did
not use interrupting signals but which used set*id() in a
multithreaded context could wrongly observe EINTR errors they're not
prepared to handle.
fix crashes in x32 __tls_get_addr 2017-01-13T10:47:08+00:00 rofl0r retnyg@gmx.net 2017-01-13T10:28:46+00:00 1f53e7d00c375efb32e2e468f91a42668653d5f0 x32 has another gratuitous difference to all other archs: it passes an array of 64bit values to __tls_get_addr(). usually it is an array of size_t. 
x32 has another gratuitous difference to all other archs:
it passes an array of 64bit values to __tls_get_addr().
usually it is an array of size_t.
rework arm atomic/tp backends to be thumb-compatible and fdpic-ready 2016-12-20T02:21:08+00:00 Rich Felker dalias@aerifal.cx 2016-12-19T00:38:53+00:00 29237f7f5c09c436825a7a12b68ab4143b0ebd1f three problems are addressed: - use of pc arithmetic, which was difficult if not impossible to make correct in thumb mode on all models, so that relative rather than absolute pointers to the backends could be used. this was designed back when there was no coherent model for the early stages of the dynamic linker before relocations, and is no longer necessary. - assumption that data (the relative pointers to the backends) can be accessed at a constant displacement from the code. this will not be possible on future fdpic subarchs (for cortex-m), so move responsibility for loading the backend code address to the caller. - hard-coded arm opcodes using the .word directive. instead, use the .arch directive to work around the assembler's refusal to assemble instructions not available (or in some cases, available but just considered deprecated) in the target isa level. the obscure v6t2 arch is used for v6 code so as to (1) allow generation of thumb2 output if -mthumb is active, and (2) avoid warnings/errors for mcr barriers that clang would produce if we just set arch to v7-a. in addition, the __aeabi_read_tp function is moved out of the inner workings and implemented as an asm wrapper around a C function, so that asm code does not need to read global data. the asm wrapper serves to satisfy the ABI calling convention requirements for this function. 
three problems are addressed:

- use of pc arithmetic, which was difficult if not impossible to make
  correct in thumb mode on all models, so that relative rather than
  absolute pointers to the backends could be used. this was designed
  back when there was no coherent model for the early stages of the
  dynamic linker before relocations, and is no longer necessary.

- assumption that data (the relative pointers to the backends) can be
  accessed at a constant displacement from the code. this will not be
  possible on future fdpic subarchs (for cortex-m), so move
  responsibility for loading the backend code address to the caller.

- hard-coded arm opcodes using the .word directive. instead, use the
  .arch directive to work around the assembler's refusal to assemble
  instructions not available (or in some cases, available but just
  considered deprecated) in the target isa level. the obscure v6t2
  arch is used for v6 code so as to (1) allow generation of thumb2
  output if -mthumb is active, and (2) avoid warnings/errors for mcr
  barriers that clang would produce if we just set arch to v7-a.

in addition, the __aeabi_read_tp function is moved out of the inner
workings and implemented as an asm wrapper around a C function, so
that asm code does not need to read global data. the asm wrapper
serves to satisfy the ABI calling convention requirements for this
function.
add s390x port 2016-11-12T04:06:21+00:00 Bobby Bingham koorogi@koorogi.info 2016-11-12T03:52:05+00:00 15094943050eb9a564f409323070e50b40f78816